1. Field of the Invention
This invention relates to a bar code reader for reading a bar code by means of irradiating a laser beam from a laser diode toward the bar code and receiving the subsequently reflected light on a photosensor.
2. Description of the Related Art
A bar code reader, for reading a bar code from the reflected light of a laser beam irradiated onto the bar code, has an advantage in that a bar code can be read regardless of any distance between the bar code and the bar code reader, and thus it is in widespread use in various fields, such as marketing and sales management, at the present time.
As an example of the above bar code readers using a laser beam, there is Japanese Patent Laid-open No. Hei 5-108860.
This bar code reader is composed of a hand-held bar code scanner 51 held by hand in use as shown in FIG. 9, and a decoder 53 decoding the bar code in accordance with a signal outputted from the bar code scanner 51.
The bar code scanner 51 is, in turn, composed of: a light source 54, such as a light-emitting diode, irradiating a laser beam (light beam) L; a lens 55 focusing the laser beam L emitted from the light source 54; a light scanner 56 for scanning the laser beam L which has passed through the lens 55; and a photosensor 58 for sensing the amount of reflected light which is scanned over the bar code 57 by the light scanner 56.
The decoder 53 decodes numerals, symbols or the like ciphered in the bar code 57 based on the amount of reflected light sensed by the photosensor 58.
One type of bar code reader is designed so that a laser beam or the like irradiated from a light source is directed to the right and left by means of a mirror, attached to a rotating shaft of a motor, to scan the bar code, and a photosensor receives the light reflected from the bar code, and then numerals, symbols or the like ciphered in the bar code are decoded from signals outputted from the photosensor.
Another type of the bar code reader is a manual type designed so that the bar code reader itself is moved along a bar code to thereby scan without the scanning mechanism, and laterally directing a laser beam irradiated from the light source.
As is clear from FIG. 9, however, the aforementioned bar code reader disclosed in Japanese Patent Laid-open No. Hei 5-108860 has a disadvantage in that the width W from the light source 54 to the photosensor 58 is increased as shown in the drawing due to the fact that the light source 54, such as a light-emitting diode, and the photosensor 58 are disposed so that the incident direction of the reflected light incident onto the photosensor 58 forms an approximate right angle or closer angle thereto with respect to the irradiating direction of the light irradiated from the light source 54.
In the bar code reader shown in FIG. 9, although the bar code reader is not moved, the laser beam L emitted from the light source 54 can be scanned over the bar code 57 by displacing the light scanner 56. There is, however, a disadvantage in which, in view of the large variation in optical paths of the laser beam L emitted from the light source 54 and the reflected light reflected from the bar code 57 and incident onto the photosensor 58, a reading end port, formed on the end of the bar code reader which is pointed toward the bar code for scanning, is required to be formed so as not to obstruct the laser beam and the reflected light.
In consequence, the reading end port of the bar code reader is naturally large and the thickness of a portion corresponding of the reading end port cannot be made compact, so that the bar code reader itself increases in size and weight, resulting in inconvenience in a hand-held type bar code reader which an operator holds by hand while in use.
To resolve the aforementioned disadvantages, it is an object of the present invention to achieve reduction in size in a bar code reader by means of an arrangement of a laser diode, irradiating a laser beam, and a photosensor, receiving a light reflected from a bar code after the laser beam is incident onto the bar code, in a small area.
In order to achieve the above object, in a bar code reader for reading a bar code by means of emitting a laser beam from a laser diode toward the bar code and receiving the subsequently reflected light on a photosensor, the photosensor is disposed along an irradiating direction of the laser beam emitted from the laser diode.
In the above arrangement, the laser diode and the photosensor can be effectively arranged in a smaller area, resulting in a reduction in size of the bar code reader.
In the above bar code reader, preferably, the laser diode and the photosensor are housed in a case, and a scanning mirror for reflecting the laser beam, emitted from the laser diode, directly or through the medium of a mirror to redirect an optical path of the laser beam; and a mirror-setting angle changing means for changing the angle of setting of the scanning mirror, are provided in the front end portion of the case in the irradiating direction of the laser beam.
In the above arrangement, although the bar code reader is not moved, the laser beam emitted from the laser diode can scan over the bar code by means of the scanning mirror displaced by the mirror-setting angle changing means.
In addition, although the laser beam is scanned in a predetermined scanning width by the displacement of the scanning mirror, since the scanning mirror and the mirror-setting angle changing means are provided in the front end portion of the case in the irradiating direction of the laser beam, the scanned laser beam passes through the front end portion of the case at a close proximity to the scanning mirror.
Consequently, even when a reading end port of the front end portion of the case comprises a smaller opening, the laser beam never hits the case, so that the size of the bar code reader can be reduced.
Moreover, the bar code reader is structured to include a case shaped to have a bent front end portion, in which the laser diode and the photosensor are housed in the inside of a portion between the bent portion and the tail portion of the case, and the scanning mirror for reflecting the laser beam, emitted from the laser diode, to redirect an optical path of the laser beam; the mirror-setting angle changing means for changing the angle of setting of the scanning mirror; and a reflected-light path changing member for reflecting the reflected light, reflected from the bar code after being reflected toward the bar code by the scanning mirror, toward the photosensor, are provided in the bent portion of the case.
According to the above arrangement, even if the bar code is located on the other side of a small hole such as a venting hole, by inserting the bent portion of the case into the hole, the laser beam emitted from the laser diode can hit the bar code at an approximate right angle, whereby the bar code is read with high accuracy.
Even when the bar code is adhered onto a surface of a box or the like facing a wall, insofar as there is a space between the wall and the surface on which the bar code is adhered, which allows the bent portion of the case to be inserted therein, the bar code can be effortlessly read by inserting the bent portion of the case into the space.
Preferably, the mirror-setting angle changing means comprises a piezoelectric element. As a result, the mirror-setting angle changing means is not a hindrance due to its smaller size and the bar code reader has a simple structure due to the fact that the mirror-setting angle changing means is easily installed and located.